IPCC AR4 CLIMATE MODEL COMPARISONS

In order to select appropriate scenarios for climate impacts
studies based on the IPCC Forth Assessment (AR4) climate simulations,
we have analyzed the climate response for the pacific northwest for
various models. For consistency with prior work, we include the
current versions of models used previously: Hadcm3, Echam5, CCSM3, and
PCM1 (CCSM3 is the successor to both the NCAR CSM and DOE PCM). To
these we added 5 additional models to better represent the range of
models participating in AR4. These are: CNRM_CM3, CSIRO_MK3 Miroc_3.2,
IPSL_CM4, CGCM_3.1, and GISS_ER.

The models represent a range of spatial resolutions. The lower
resolution models, run at T42 (64x128), are similar to the resolution
used in previous work. However, a number of models are now run at much
higher resolution of T63 (96x192) or T85
(128x256). This table
summarizes the resolutions for the various models.

Each section below presents results from the analysis with some
discussion of the results.